1. Field of the Invention
The present invention relates to a bed structure for a free arm type overlock machine.
2. Related Art
The overlock machine forms overlock sews by the cooperative operations of a vertically movable needle holding a needle thread, an upper looper holding an upper looper thread and operates across a workpiece feed direction, and a lower looper holding a lower looper thread. The free arm type overlock machine, in general, has replaceable accessories including a free arm cover and an auxiliary bed. Only the free arm cover is used for sewing cylindrical workpieces, such as cuffs and the bottom edges of pants legs, and pouches. The auxiliary bed is used, in combination with the free arm cover, for sewing ordinary fiat workpieces. Although the free arm type overlock machine is well adapted to sew cylindrical workpieces and pouches, it is difficult to sew fiat workpieces because the free arm has a narrow supporting area. Therefore, the auxiliary bed is attached to the free arm to provide a wide supporting area for sewing fiat workpieces. The free arm cover of the free arm type overlock machine must be removed in threading the lower looper. If the auxiliary bed is attached to the free arm, the auxiliary bed must be removed before removing the free arm cover, which requires additional work for threading the lower looper.